Class ColumnMetaData

Meta data of a column

@note The encoding used for the different bytes fields in the meta data is externally controlled. See also: https://dev.mysql.com/doc/refman/5.0/en/charset-connection.html

@par @note The server may not set the original_{table|name} fields if they are equal to the plain {table|name} field.

@par @note A client has to reconstruct it like: @code{py} if .original_name is empty and .name is not empty: .original_name = .name

if .original_table is empty and .table is not empty: .original_table = .table @endcode

@par @note Compact metadata format can be requested by the client. In that case, only .type is set and all other fields are empty.

Expected data type of Mysqlx.Resultset.Row per SQL Type for non-NULL values:

SQL Type .type .length .frac_dig .flags .charset
TINY SINT x
TINY UNSIGNED UINT x x
SHORT SINT x
SHORT UNSIGNED UINT x x
INT24 SINT x
INT24 UNSIGNED UINT x x
INT SINT x
INT UNSIGNED UINT x x
LONGLONG SINT x
LONGLONG UNSIGNED UINT x x
DOUBLE DOUBLE x x x
FLOAT FLOAT x x x
DECIMAL DECIMAL x x x
VARCHAR,CHAR,... BYTES x x x
GEOMETRY BYTES
TIME TIME x
DATE DATETIME x
DATETIME DATETIME x
YEAR UINT x x
TIMESTAMP DATETIME x
SET SET x
ENUM ENUM x
NULL BYTES
BIT BIT x

@note The SQL "NULL" value is sent as an empty field value in @ref Mysqlx::Resultset::Row.

@par Tip The protobuf encoding of primitive data types is described in https://developers.google.com/protocol-buffers/docs/encoding

  • SINT
  • .length @n Maximum number of displayable decimal digits (including minus sign) of the type. @note The valid range is 0-255, but usually you'll see 1-20.
SQL Type Maximum Digits per Type
TINY SIGNED 4
SHORT SIGNED 6
INT24 SIGNED 8
INT SIGNED 11
LONGLONG SIGNED 20

@par Tip Definition of M are in https://dev.mysql.com/doc/refman/5.5/en/numeric-type-overview.html.

  • value@n Variable length encoded signed 64 integer.
  • UINT

  • .flags & 1 (zerofill) @n The client has to left pad with 0's up to .length.

  • .length @n Maximum number of displayable decimal digits of the type. @note The valid range is 0-255, but usually you'll see 1-20.

SQL Type max digits per type
TINY UNSIGNED 3
SHORT UNSIGNED 5
INT24 UNSIGNED 8
INT UNSIGNED 10
LONGLONG UNSIGNED 20

@par Tip Definition of M are in https://dev.mysql.com/doc/refman/5.5/en/numeric-type-overview.html.

  • value @n Variable length encoded unsigned 64 integer.
  • BIT
  • .length @n Maximum number of displayable binary digits. @note The valid range for M of the BIT type is 1 - 64.

@par Tip https://dev.mysql.com/doc/refman/5.5/en/numeric-type-overview.html

  • value @n Variable length encoded unsigned 64 integer.
  • DOUBLE

  • .length @n Maximum number of displayable decimal digits (including the decimal point and .fractional_digits).

  • .fractional_digits @n Maximum number of displayable decimal digits following the decimal point.

  • value@n Encoded as protobuf's 'double'.

  • FLOAT

  • .length@n Maximum number of displayable decimal digits (including the decimal point and .fractional_digits).

  • .fractional_digits@n Maximum number of displayable decimal digits following the decimal point.

  • value@n Encoded as protobuf's 'float'.

  • BYTES, ENUM @note BYTES is used for all opaque byte strings that may have a charset:

  • TINYBLOB, BLOB, MEDIUMBLOB, LONGBLOB

  • TINYTEXT, TEXT, MEDIUMTEXT, LONGTEXT

  • VARCHAR, VARBINARY

  • CHAR, BINARY

  • ENUM

  • .length@n Maximum length of characters of the underlying type.

  • .flags & 1 (rightpad) @n If the length of the field is less than .length, the receiver is supposed to add padding characters to the right end of the string. If the .charset is "binary", the padding character is 0x00, otherwise it is a space character as defined by that character set. | SQL Type | .length | .charset | .flags | |---------------|----------|-----------|----------| | TINYBLOB | 256 | binary | | | BLOB | 65535 | binary | | | VARCHAR(32) | 32 | utf8 | | | VARBINARY(32) | 32 | utf8_bin | | | BINARY(32) | 32 | binary | rightpad | | CHAR(32) | 32 | utf8 | rightpad |

  • value Sequence of bytes with added one extra 0x00 byte at the end. To obtain the original string, the extra 0x00 should be removed. The length of the string can be acquired with protobuf's field length() method:

length of sequence-of-bytes = length-of-field - 1 @note The extra byte allows to distinguish between a NULL and empty byte sequence.

  • TIME

A time value.

  • value@n The following bytes sequence:

negate [ hour [ minutes [ seconds [ useconds ]]]]

  • negate - one byte, should be one of: 0x00 for "+", 0x01 for "-"

  • hour - optional variable length encoded unsigned64 value for the hour

  • minutes - optional variable length encoded unsigned64 value for the minutes

  • seconds - optional variable length encoded unsigned64 value for the seconds

  • useconds - optional variable length encoded unsigned64 value for the microseconds

@par Tip The protobuf encoding in https://developers.google.com/protocol-buffers/docs/encoding.

@note Hour, minutes, seconds, and useconds are optional if all the values to the right are 0.

Example: 0x00 -> +00:00:00.000000

  • DATETIME

A date or date and time value.

  • value @n A sequence of variants, arranged as follows:

| year | month | day | [ | hour | [ | minutes | [ | seconds | [ | useconds | ]]]]

  • year - variable length encoded unsigned64 value for the year

  • month - variable length encoded unsigned64 value for the month

  • day - variable length encoded unsigned64 value for the day

  • hour - optional variable length encoded unsigned64 value for the hour

  • minutes - optional variable length encoded unsigned64 value for the minutes

  • seconds - optional variable length encoded unsigned64 value for the seconds

  • useconds - optional variable length encoded unsigned64 value for the microseconds @note Hour, minutes, seconds, useconds are optional if all the values to the right are 0.

  • .flags@n | Name | Position | |---------------|----------| | is_timestamp | 1 |

  • DECIMAL

An arbitrary length number. The number is encoded as a single byte indicating the position of the decimal point followed by the Packed BCD encoded number. Packed BCD is used to simplify conversion to and from strings and other native arbitrary precision math data types. See also: packed BCD in https://en.wikipedia.org/wiki/Binary-coded_decimal

  • .length Maximum number of displayable decimal digits (excluding the decimal point and sign, but including .fractional_digits). @note Should be in the range of 1 - 65.

  • .fractional_digits The decimal digits to display out of length. @note Should be in the range of 0 - 30.

value The following bytes sequence:

scale | BCD+ sign [0x00]?

  • scale - 8bit scale value (number of decimal digit after the '.')

  • BCD - BCD encoded digits (4 bits for each digit)

  • sign - sign encoded on 4 bits (0xc = "+", 0xd = "-")

  • 0x0 - last 4bits if length(digits) % 2 == 0

Example: x04 0x12 0x34 0x01 0xd0 -> -12.3401

  • SET

A list of strings representing a SET of values.

  • value@n A sequence of 0 or more of protobuf's bytes (length prepended octets) or one of the special sequences with a predefined meaning listed below.

Example (length of the bytes array shown in brackets):

  • [0] - the NULL value

  • [1] 0x00 - a set containing a blank string ''

  • [1] 0x01 - this would be an invalid value, but is to be treated as the empty set

  • [2] 0x01 0x00 - a set with a single item, which is the '0' character

  • [8] 0x03 F O O 0x03 B A R - a set with 2 items: FOO,BAR

Inheritance
System.Object
ColumnMetaData
Implements
Google.Protobuf.IBufferMessage
Namespace: Mysqlx.Resultset
Assembly: MySql.Data.dll
Version: 9.2.0
Syntax
public sealed class ColumnMetaData : Google.Protobuf.IMessage<ColumnMetaData>

Constructors

ColumnMetaData()

Declaration
public ColumnMetaData()

ColumnMetaData(ColumnMetaData)

Declaration
public ColumnMetaData(ColumnMetaData other)
Parameters
Type Name Description
ColumnMetaData other

Fields

CatalogFieldNumber

Field number for the "catalog" field.

Declaration
public const int CatalogFieldNumber = 7
Field Value
Type Description
System.Int32

CollationFieldNumber

Field number for the "collation" field.

Declaration
public const int CollationFieldNumber = 8
Field Value
Type Description
System.Int32

ContentTypeFieldNumber

Field number for the "content_type" field.

Declaration
public const int ContentTypeFieldNumber = 12
Field Value
Type Description
System.Int32

FlagsFieldNumber

Field number for the "flags" field.

Declaration
public const int FlagsFieldNumber = 11
Field Value
Type Description
System.Int32

FractionalDigitsFieldNumber

Field number for the "fractional_digits" field.

Declaration
public const int FractionalDigitsFieldNumber = 9
Field Value
Type Description
System.Int32

LengthFieldNumber

Field number for the "length" field.

Declaration
public const int LengthFieldNumber = 10
Field Value
Type Description
System.Int32

NameFieldNumber

Field number for the "name" field.

Declaration
public const int NameFieldNumber = 2
Field Value
Type Description
System.Int32

OriginalNameFieldNumber

Field number for the "original_name" field.

Declaration
public const int OriginalNameFieldNumber = 3
Field Value
Type Description
System.Int32

OriginalTableFieldNumber

Field number for the "original_table" field.

Declaration
public const int OriginalTableFieldNumber = 5
Field Value
Type Description
System.Int32

SchemaFieldNumber

Field number for the "schema" field.

Declaration
public const int SchemaFieldNumber = 6
Field Value
Type Description
System.Int32

TableFieldNumber

Field number for the "table" field.

Declaration
public const int TableFieldNumber = 4
Field Value
Type Description
System.Int32

TypeFieldNumber

Field number for the "type" field.

Declaration
public const int TypeFieldNumber = 1
Field Value
Type Description
System.Int32

Properties

Catalog

  • catalog the schema originates from @note As there is currently no support for catalogs in MySQL, don't expect this field to be set. In the MySQL C/S protocol the field had the value def all the time
Declaration
public Google.Protobuf.ByteString Catalog { get; set; }
Property Value
Type Description
Google.Protobuf.ByteString

Collation

Declaration
public ulong Collation { get; set; }
Property Value
Type Description
System.UInt64

ContentType

  • a hint about the higher-level encoding of a BYTES field | Type | Value | Description | |--------|--------|-------------------------| | BYTES | 0x0001 | GEOMETRY (WKB encoding) | | BYTES | 0x0002 | JSON (text encoding) | | BYTES | 0x0003 | XML (text encoding) | @note This list isn't comprehensive. As a guideline: the field's value is expected to pass a validator check on client and server if this field is set. If the server adds more internal data types that rely on BLOB storage like image manipulation, seeking into complex types in BLOBs, and more types will be added
Declaration
public uint ContentType { get; set; }
Property Value
Type Description
System.UInt32

Descriptor

Declaration
public static Google.Protobuf.Reflection.MessageDescriptor Descriptor { get; }
Property Value
Type Description
Google.Protobuf.Reflection.MessageDescriptor

Flags

  • .type specific flags | Type | Value | Description | |---------|--------|--------------| | UINT | 0x0001 | zerofill | | DOUBLE | 0x0001 | unsigned | | FLOAT | 0x0001 | unsigned | | DECIMAL | 0x0001 | unsigned | | BYTES | 0x0001 | rightpad |
Value Description
0x0010 NOT_NULL
0x0020 PRIMARY_KEY
0x0040 UNIQUE_KEY
0x0080 MULTIPLE_KEY
0x0100 AUTO_INCREMENT

default: 0

Declaration
public uint Flags { get; set; }
Property Value
Type Description
System.UInt32

FractionalDigits

  • displayed factional decimal digits for floating point and fixed point numbers
Declaration
public uint FractionalDigits { get; set; }
Property Value
Type Description
System.UInt32

HasCatalog

Gets whether the "catalog" field is set

Declaration
public bool HasCatalog { get; }
Property Value
Type Description
System.Boolean

HasCollation

Gets whether the "collation" field is set

Declaration
public bool HasCollation { get; }
Property Value
Type Description
System.Boolean

HasContentType

Gets whether the "content_type" field is set

Declaration
public bool HasContentType { get; }
Property Value
Type Description
System.Boolean

HasFlags

Gets whether the "flags" field is set

Declaration
public bool HasFlags { get; }
Property Value
Type Description
System.Boolean

HasFractionalDigits

Gets whether the "fractional_digits" field is set

Declaration
public bool HasFractionalDigits { get; }
Property Value
Type Description
System.Boolean

HasLength

Gets whether the "length" field is set

Declaration
public bool HasLength { get; }
Property Value
Type Description
System.Boolean

HasName

Gets whether the "name" field is set

Declaration
public bool HasName { get; }
Property Value
Type Description
System.Boolean

HasOriginalName

Gets whether the "original_name" field is set

Declaration
public bool HasOriginalName { get; }
Property Value
Type Description
System.Boolean

HasOriginalTable

Gets whether the "original_table" field is set

Declaration
public bool HasOriginalTable { get; }
Property Value
Type Description
System.Boolean

HasSchema

Gets whether the "schema" field is set

Declaration
public bool HasSchema { get; }
Property Value
Type Description
System.Boolean

HasTable

Gets whether the "table" field is set

Declaration
public bool HasTable { get; }
Property Value
Type Description
System.Boolean

HasType

Gets whether the "type" field is set

Declaration
public bool HasType { get; }
Property Value
Type Description
System.Boolean

Length

  • maximum count of displayable characters of .type
Declaration
public uint Length { get; set; }
Property Value
Type Description
System.UInt32

Name

  • name of the column
Declaration
public Google.Protobuf.ByteString Name { get; set; }
Property Value
Type Description
Google.Protobuf.ByteString

OriginalName

  • name of the column before an alias was applied
Declaration
public Google.Protobuf.ByteString OriginalName { get; set; }
Property Value
Type Description
Google.Protobuf.ByteString

OriginalTable

  • name of the table the column originates from before an alias was applied
Declaration
public Google.Protobuf.ByteString OriginalTable { get; set; }
Property Value
Type Description
Google.Protobuf.ByteString

Parser

Declaration
public static Google.Protobuf.MessageParser<ColumnMetaData> Parser { get; }
Property Value
Type Description
Google.Protobuf.MessageParser<ColumnMetaData>

Schema

  • schema the column originates from
Declaration
public Google.Protobuf.ByteString Schema { get; set; }
Property Value
Type Description
Google.Protobuf.ByteString

Table

  • name of the table the column originates from
Declaration
public Google.Protobuf.ByteString Table { get; set; }
Property Value
Type Description
Google.Protobuf.ByteString

Type

  • datatype of the field in a row
Declaration
public ColumnMetaData.Types.FieldType Type { get; set; }
Property Value
Type Description
ColumnMetaData.Types.FieldType

Methods

CalculateSize()

Declaration
public int CalculateSize()
Returns
Type Description
System.Int32

ClearCatalog()

Clears the value of the "catalog" field

Declaration
public void ClearCatalog()

ClearCollation()

Clears the value of the "collation" field

Declaration
public void ClearCollation()

ClearContentType()

Clears the value of the "content_type" field

Declaration
public void ClearContentType()

ClearFlags()

Clears the value of the "flags" field

Declaration
public void ClearFlags()

ClearFractionalDigits()

Clears the value of the "fractional_digits" field

Declaration
public void ClearFractionalDigits()

ClearLength()

Clears the value of the "length" field

Declaration
public void ClearLength()

ClearName()

Clears the value of the "name" field

Declaration
public void ClearName()

ClearOriginalName()

Clears the value of the "original_name" field

Declaration
public void ClearOriginalName()

ClearOriginalTable()

Clears the value of the "original_table" field

Declaration
public void ClearOriginalTable()

ClearSchema()

Clears the value of the "schema" field

Declaration
public void ClearSchema()

ClearTable()

Clears the value of the "table" field

Declaration
public void ClearTable()

ClearType()

Clears the value of the "type" field

Declaration
public void ClearType()

Clone()

Declaration
public ColumnMetaData Clone()
Returns
Type Description
ColumnMetaData

Equals(ColumnMetaData)

Declaration
public bool Equals(ColumnMetaData other)
Parameters
Type Name Description
ColumnMetaData other
Returns
Type Description
System.Boolean

Equals(Object)

Declaration
public override bool Equals(object other)
Parameters
Type Name Description
System.Object other
Returns
Type Description
System.Boolean

GetHashCode()

Declaration
public override int GetHashCode()
Returns
Type Description
System.Int32

MergeFrom(Google.Protobuf.CodedInputStream)

Declaration
public void MergeFrom(Google.Protobuf.CodedInputStream input)
Parameters
Type Name Description
Google.Protobuf.CodedInputStream input

MergeFrom(ColumnMetaData)

Declaration
public void MergeFrom(ColumnMetaData other)
Parameters
Type Name Description
ColumnMetaData other

ToString()

Declaration
public override string ToString()
Returns
Type Description
System.String

WriteTo(Google.Protobuf.CodedOutputStream)

Declaration
public void WriteTo(Google.Protobuf.CodedOutputStream output)
Parameters
Type Name Description
Google.Protobuf.CodedOutputStream output

Implements

Google.Protobuf.IBufferMessage